This invention is concerned with a method of forming an abrasion-resistant coating on molded polymeric articles.
In Japanese Pat. No. 74-45965 issued May 2, 1974 a method is described for providing an abrasion-resistant coating on a molded article formed by curing a polymerizable monomer-containing molding composition in a mold. The method comprises applying a film of a coating composition comprising low viscosity polymerizable monomers such as trimethylolpropane triacrylate, butanediol diacrylate and benzoin methyl ether to the inside surface of a glass mold, exposing said coating composition to UV radiation first in a nitrogen atmosphere and then in air to form a cured coating in the mold, adding to the mold a molding syrup comprising methyl methacrylate monomer and azobisisobutyronitrile; and heating said mold to polymerize said molding composition in the form of a molded article, whereby the cured coating is transferred from the glass mold surface to the molded article.
The present invention provides a method for coating a molded article in situ with a radiation curable coating composition comprising a pentaerythritol-based polyacrylate or polymethacrylate and a cellulose ester or a vinyl chloride-vinyl acetate containing copolymer. The composition when applied in the method can be cured without the necessity of a nitrogen or other inert atmosphere to provide a highly abrasion-resistant coating on the formed article which is also resistant to solvents and chemicals.